Zonal stratification and geographic clustering of a species-rich chironomid community in freshwater coastal rock pools

Chironomidae are typically abundant in freshwater habitats and can be good indicators of ecological health. Coastal rock pools of barrier islands were sampled to determine how communities varied spatially between two horizontal zones, defined by wave disturbance and distance from shore, and from island-to-island. Pupal exuviae were collected monthly from pool surfaces to assess species composition, true community richness, and alpha and beta diversity. Cluster analyses were used to determine geographic community variation. A majority of species were rare, while three species dominated relative abundances. Zonal differences were significant, diversity was greater in near-shore pools overall, and few species occurred in both zones. Communities were more species-rich than expected based on prior studies in similar habitats. Community clusters were not strongly differentiated but suggested increased dispersal challenges at wider gaps between islands. Higher diversity near the shore and geographic clustering of communities are important to consider when planning for remediation activities following pollution events such as ship groundings or oil spills. In general, baseline coastal studies and conservation planning should consider aquatic invertebrates when pool habitats are present.